duete; see due, ty 2 ]. syn: duty, obligation refer to something a person feels bound to do. A duty often applies to what a person performs in fulfillment of the permanent dictates of conscience, piety, right, or law: one's duty to tell the truth; a parent's duty to raise children properly.
Mutations in the RB1 gene are responsible for most cases of retinoblastoma. RB1 is a tumor suppressor gene, which means that it normally regulates cell growth and keeps cells from dividing too rapidly or in an uncontrolled way.
Causes of retinal migraine. Retinal migraine is caused by the blood vessels to the eye suddenly narrowing (constricting), reducing the bloodflow to the eye. Afterwards the blood vessels relax, bloodflow resumes and sight returns. Usually there are no abnormalities within the eye and permanent damage to the eye is rare.